In recent years, Chinese government pays much more attention on energy saving and has a goal of reducing national energy consumption of 20%. With the successive promulgations of the national energy-saving policies, energy saving has raised an upsurge throughout the whole country.
In the energy-saving upsurge, energy-efficient window film has become the biggest highlight of the new economic growth. Throughout the Chinese window film market, the potential demands for window film are amazing in construction industry, automobile industry and IT products. Therefore, it has important strategic significance to synthesize composite window film by use of the burgeoning organic-inorganic nanoparticle composite technology.
In recent years, our country witnessed economic prosperity and rapid development of the urban construction. All cities were decorated gorgeously and colorfully by splendid modern buildings. However, the development of the urban construction also brought social problems of high energy and resource consumption. Relevant statistics show that currently China's construction energy consumption accounts for 40% of the social energy consumption; the energy consumption of indoor heating and air conditioning refrigeration accounts for about 65% of the construction energy consumption. What is more shocking is that more than 50% of the temperature control energy efficiency brought by heating and air conditioning is lost from building windows having an energy-saving effect that is not ideal. As can be seen, energy-saving remodeling of doors and windows is critical in the energy saving for existing buildings. To this end, it has become an urgent demand for the sustainable development of our country to reduce the high construction energy consumption, which has also become the focus of the current work in our country. Now in many developed European and American countries, in order to improve the energy-saving efficiency of windows and doors, more than 70% of the buildings are subject to energy-saving remodeling with energy-saving window film. This is experience that is worth learning and also provides a rare opportunity for the development of energy-saving glass in our country.
For the time being, the energy-saving window films in the market of our country are mainly dominated by several big foreign brands including V-KOOL, Ray-Ban, 3M, ATI and Johnson. The market lacks products of local independent brands, which provides a broad space for development of the local energy-saving window film in our country and provides impetus for the development of the technology for preparing energy-saving window film.
It is well known that UV ray, as a non-visual ray, has specific lethality and is referred to as “invisible killer” in the scientific community. UV rays, according to the wavelength, can be divided into: UV-A waveband having a wavelength of 320˜400 nm, UV-B having a wavelength of 280˜320 nm, UV-C having a wavelength of 100˜280 nm. UV-C can pass through the dermis. UV-B can enter the dermis. A great part of UV-B can be absorbed by the skin and impair DNA. When DNA is impaired, cells will die or develop into uncontrollable cancer cells. The inducements of many diseases able to be diagnosed currently are related with UV radiation. Since the 1920s, due to the heavy use of fluorocarbon solvents and freon, the atmospheric ozone layer has been seriously damaged, causing the continuous increase of UV rays reaching the earth's surface. For this reason, people spent a great deal of manpower and resources to take effective protective measures against the “invisible killer”, researched and developed a variety of anti-UV materials. Multiple UV-blocking materials are currently available on the market. However, the existing UV-blocking materials still have deficiencies such as: a low visible light transmittance, no absorption of infrared region and high processing and production cost and have large space for improvement.
Many UV-blocking films and infrared heat-insulating film materials on the current market are prepared with organic high molecular polymer as the substrate. Thus the film itself also has certain flammability. For the time being, the film material can not only be applied in such transparent materials and items as glass, windows, protective films, containers and electronic components but also widely used in such fields as construction, transportation, electronics, aerospace and medicine. In the specific fields, polymer materials account for a large proportion, so that the flame retardant property of the film material in the fields is particularly important. Moreover, in the traditional application field of the film material (e.g., construction industry and automobile industry), construction materials like glass that are originally non-combustible, after being coated with various functional film products on the surface, are extremely likely to become transmitting media for fire source or flame. Accordingly, it has significant meaning to research and develop a window film incorporating many functions including flame retardance, UV blocking and infrared shielding, which also has broad market prospect.